But of that per centage in WW2, only about one in five Americans were actual combat troops. Others were medics or in transport and supply. Conversely in the German Army the ratio was one in three. But towards the end of the war any and every German male old enough to field a weapon was sent to fight.
And large numbers of runaway slaves, contrabands, were used by the US army in support and labor roles without being enlisted in the USCT.